1. Field of the Invention
The present invention relates to a storage apparatus used in a computer system and, more particularly, to a storage apparatus using non-volatile semiconductor memories such as flash memories as memory media thereof, a memory area managing method of the apparatus, and a flash memory package.
2. Description of the Related Art
In general, a storage apparatus includes random-accessible non-volatile memory media. For example, the random-accessible non-volatile memory media may be magnetic disks (hereinafter referred to as hard disks) or optical disks, and a configuration including a multiplicity of hard disks is employed as described in Patent Document 1 (listed ahead).
Recently, more attention is paid to storage apparatus employing non-volatile semiconductor memories such as flash memories as memory media, to replace hard disks used in the related art. A flash memory is more advantageous than a hard disk in that it can operate at a higher speed with less power consumption. Patent Document 2 (listed ahead) discloses a technique used in a storage apparatus to allow a hard disk used in the storage apparatus to be replaced with a flash memory disk which includes a plurality of flash memories and which can be accessed using a hard disk accessing device according to the related art such as an SCSI (Small Computer System Interface).
Patent Document 3 (listed ahead) discloses a method of allowing a flash memory to be efficiently written. According to the method, a block in a flash memory is divided into a write area and a data area, and write data is additionally written in the form of logs in the write area. When a certain amount of data is accumulated in the write area, the data in the block is read into a memory to overwrite the memory with the data in the write area. Thereafter, the data is written in the data area. Such a writing method is called a reclamation method.    Patent Document 1: JP-A-2004-5370    Patent Document 2: U.S. Pat. No. 6,529,416    Patent Document 3: U.S. Pat. No. 7,039,788
When it is attempted to improve write performance by dividing a region of a flash memory into a data area and a write area as described above, substantially no reclamation of the write area occurs in some occasions where there is a small number of write instructions (a.k.a write or write command), depending on the application executed by the host computer of the memory. A problem then arises in that the write area thus allocated will not be efficiently used.
In order to solve the above-described problem, it is desirable to provide a storage apparatus which allows a write area associated with a data area of interest to be allocated in accordance with the write performance of its host computer.
When the write area is reduced in accordance with write performance, the number of the relevant flash memory packages must be also reduced in accordance with the write performance.